1. Field of the Invention
The present invention relates to the field of pipelined ADCs (analog to digital converters).
2. Prior Art
Pipelined ADCs and flash ADCs are well known in the prior art. Good reviews of the principles thereof can be found in Maxim Integrated Products'. Application Note 1023 “Understanding Pipelined ADCs”, and in Maxim Integrated Products' Application Note 810 “Understanding Flash ADCs”, respectively. A pipelined ADC typically has a sample and hold circuit on the analog signal input, which dissipates power and injects noise into the ADC. This problem is addressed in prior art by completely eliminating the sample and hold and sampling directly onto the first MDAC (multiplying digital to analog converter) capacitors. In this prior art implementation, an independent sampler in parallel with the MDAC is required for the comparators.
Also known are ADCs that use a shared operational transconductance amplifier (OTA). In such implementations, a single OTA is shared during different phases by multiple multiplying digital to analog converters.